The starting point of the present invention lies in the specialist medical field of what are known as ablation catheters, with which areas of biological tissue can be cauterized or tissue parts can be removed, and even more specifically in ablation catheters with contact force measurement.
An ablation catheter (e.g., “TactiCath”, manufactured by Endosense) is known which enables the measurement of a force acting on the distal catheter end (that is to say of the aforementioned contact force during use) in terms of magnitude and direction during an ablation procedure. This catheter uses the principle of what is known as an FBG (“Fiber Bragg Grating”) sensor, wherein three fibers, each with an FBG sensor at the fiber end, form the group of sensors required for a 3-dimensional (“3D”) force measurement and can be connected to a signal processing unit for joint measurement signal processing. The sensors are fitted externally on a deformable cylinder with an angular spacing of 120°.
In U.S. Publication No. 2008/0285909, the operating principle of FBG sensors for determining twists or curvatures of the catheter body is described in detail, and the operating principle of the aforementioned force sensor comprising a plurality of FBG fibers on a deformable cylinder is also explained in this document.
In European Patent No. 2 491 883, which can be traced back to the Applicant, an ablation catheter of simplified structure with contact force measurement is described, said ablation catheter containing an individual FBG fiber comprising a plurality of sensor regions distanced from one another in the longitudinal direction. These sensor regions are arranged and formed and suitably read out in such a way that the spatial force components of a force acting on the catheter end can be determined; and additionally it is also possible to obtain temperature signals for the correction of the force measurement signals.
Independently of this measuring principle, other solutions for a contact force measurement on a guide wire or catheter are also known, for example, with use of an optical sensor, as described in International Publication No. WO2009/007857, or with use of a semiconductor sensor at the tip of a guide wire, as described in International Publication No. WO2008/003307.
Multi-axis force sensors and torque sensors have long been known in a wide range of embodiments outside the aforementioned technical field, and there are also embodiments in which printed circuit boards are used; see e.g., International Publication No. WO2010/088922.
With the construction of sensor connection elements of the aforementioned type that are suitable for series production, it has been found that the previously known superstructures are not optimal from a technological viewpoint and, in particular, impose certain limits on the automation of the production, thus leading to relatively high production costs.
The present invention is directed toward overcoming one or more of the above-mentioned problems.